Organic light emitting device

ABSTRACT

The present specification relates to an organic light emitting device including: a cathode; an anode; a light emitting layer provided between the cathode and the anode; and one or more organic material layers provided between the cathode and the light emitting layer.

This application is a National Stage Application of InternationalApplication No. PCT/KR2015/014214, filed Dec. 23, 2015, and claims thebenefit of Korean Patent Application No. 10-2015-0036097, filed Mar. 16,2015, contents of which are incorporated herein by reference in theirentirety for all purposes as if fully set forth below.

TECHNICAL FIELD

The present specification claims priority to and the benefit of KoreanPatent Application No. 10-2015-0036097 filed in the Korean IntellectualProperty Office on Mar. 16, 2015, the entire contents of which areincorporated herein by reference.

The present specification relates to an organic light emitting device.

BACKGROUND ART

An organic light emission phenomenon is one of the examples ofconverting current into visible rays through an internal process of aspecific organic molecule. The principle of the organic light emissionphenomenon is as follows.

When an organic material layer is disposed between an anode and acathode, if voltage is applied between the two electrodes, electrons andholes are injected into the organic material layer from the cathode andthe anode, respectively. The electrons and the holes which are injectedinto the organic material layer are recombined to form an exciton, andthe exciton falls down again to the ground state to emit light. Anorganic light emitting device using this principle may be composed of acathode, an anode, and an organic material layer disposed therebetween,for example, an organic material layer including a hole injection layer,a hole transporting layer, a light emitting layer, and an electrontransporting layer.

The materials used in the organic light emitting device are mostly pureorganic materials or complex compounds in which organic materials andmetals form a complex compound, and may be classified into a holeinjection material, a hole transporting material, a light emittingmaterial, an electron transporting material, an electron injectionmaterial, and the like according to the use thereof. Here, an organicmaterial having a p-type property, that is, an organic material, whichis easily oxidized and electrochemically stable when the material isoxidized, is usually used as the hole injection material or the holetransporting material. Meanwhile, an organic material having an n-typeproperty, that is, an organic material, which is easily reduced andelectrochemically stable when the material is reduced, is usually usedas the electron injection material or the electron transportingmaterial. As the light emitting layer material, a material having bothp-type and n-type properties, that is, a material, which is stableduring both the oxidation and reduction states, is preferred, and whenan exciton is formed, a material having high light emitting efficiencyfor converting the exciton into light is preferred.

There is a need in the art for developing an organic light emittingdevice having high efficiency.

CITATION LIST Patent Document

Official Gazette of Korean Patent Application Laid-Open No. 2011-0027635

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

An object of the present specification is to provide an organic lightemitting device having excellent light emission and service lifecharacteristics.

Technical Solution

An exemplary embodiment of the present specification provides an organiclight emitting device including:

a cathode; an anode; a light emitting layer provided between the cathodeand the anode; and

one or more organic material layers provided between the cathode and thelight emitting layer,

in which one or more layers of the organic material layers providedbetween the cathode and the light emitting layer include: a compoundincluding a heteroatom; and an alkali metal complex or an alkaline earthmetal complex, and

at least one of the heteroatoms of the compound including the heteroatomand the alkali metal complex or the alkaline earth metal complex aredocked to each other,

the compound including the heteroatom before the docking has a dipolemoment of less than 6 debye, and

the compound including the heteroatom after the docking has a dipolemoment of 6 debye to 13 debye.

Advantageous Effects

An organic light emitting device according to an exemplary embodiment ofthe present specification has excellent electron and hole mobility atlow driving voltage, and thus provides high light emitting efficiency.

Further, the organic light emitting device according to an exemplaryembodiment of the present specification has excellent durability becauseelectrons at each layer thereof move smoothly, and thus has excellentservice life characteristics.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating an organic light emitting device accordingto an exemplary embodiment of the present specification.

FIG. 2 is a view illustrating an organic light emitting device accordingto an exemplary embodiment of the present specification.

FIG. 3 is a view illustrating an organic light emitting device accordingto an exemplary embodiment of the present specification.

EXPLANATION OF REFERENCE NUMERALS AND SYMBOLS

-   -   101: Substrate    -   201: Anode    -   301: Hole transporting layer    -   401: Light emitting layer    -   402: Second light emitting layer    -   403: First light emitting layer    -   501: Electron transporting layer    -   601: Cathode

BEST MODE

Hereinafter, the present specification will be described in more detail.

When one member is disposed “on” another member in the presentspecification, this includes not only a case where the one member isbrought into contact with another member, but also a case where stillanother member is present between the two members.

When one part “includes” one constituent element in the presentspecification, unless otherwise specifically described, this does notmean that another constituent element is excluded, but means thatanother constituent element may be further included.

An exemplary embodiment of the present specification provides an organiclight emitting device including: a cathode; an anode; a light emittinglayer provided between the cathode and the anode; and

one or more organic material layers provided between the cathode and thelight emitting layer,

in which one or more layers of the organic material layers providedbetween the cathode and the light emitting layer include: a compoundincluding a heteroatom; and an alkali metal complex or an alkaline earthmetal complex, and

at least one of the heteroatoms of the compound including the heteroatomand the alkali metal complex or the alkaline earth metal complex aredocked to each other,

the compound including the heteroatom before the docking has a dipolemoment of less than 6 debye, and

the compound including the heteroatom after the docking has a dipolemoment of 6 debye to 13 debye.

As in an exemplary embodiment of the present specification, when thedipole moment of the compound including the heteroatom before theheteroatom and the alkali metal complex or the alkaline earth metalcomplex are docked to each other is less than 6 debye, the stability ofthe compound is better than the case where the compound has a dipolemoment of 6 debye or more. However, when the compound having a dipolemoment of less than 6 debye is used for an organic material layer, theorganic light emitting device may be disadvantageous in terms of theefficiency of the diode. Accordingly, the present invention enhances theefficiency of the diode by adjusting the dipole moment to 6 debye to 13debye through the docking of the heteroatom to the alkali metal complexor the alkaline earth metal complex.

Accordingly, as in an exemplary embodiment of the present specification,when the dipole moment is in the range before and after the heteroatomand the alkali metal complex or the alkaline earth metal complex aredocked to each other, an organic light emitting device having lowdriving voltage, high efficiency, and a long service life may beexpected.

The term “docking” in the present specification may mean that aheteroatom of a compound including the heteroatom and an alkali metalcomplex or an alkaline earth metal complex combine with each other bymeans of London dispersion forces or dipole-induced dipole forces.Specifically, a heteroatom of the compound including the heteroatom maybe docked to an alkali metal or an alkaline earth metal of the alkalimetal complex or the alkaline earth metal complex.

In the present specification, the term “complex” in the alkali metalcomplex and the alkaline earth metal complex may mean that an alkalimetal or an alkaline earth metal and atoms or molecules combine witheach other to form one molecule.

The dipole moment in the present specification is a physical quantitywhich indicates the degree of polarity, and may be calculated by thefollowing Equation 1.

$\begin{matrix}{{{p(r)} = {\int_{V}{{\rho( r_{0} )}( {r_{0} - r} )d^{3}r_{0}}}}{{\rho( r_{0} )}\text{:}\mspace{14mu}{molecular}\mspace{14mu}{density}}{V\text{:}\mspace{14mu}{volume}}{r\text{:}\mspace{14mu}{the}\mspace{14mu}{point}\mspace{14mu}{of}\mspace{14mu}{observation}}{d^{3}r_{0}\text{:}\mspace{14mu}{an}\mspace{14mu}{elementary}\mspace{14mu}{volume}}} & \lbrack {{Equation}\mspace{14mu} 1} \rbrack\end{matrix}$

The value of the dipole moment may be obtained by calculating themolecular density in Equation 1. For example, the molecular density maybe obtained by using a method called Hirshfeld Charge Analysis to obtaina charge and a dipole for each atom and performing the calculationaccording to the following equations, and the dipole moment may beobtained by substituting the Equation 1 with the calculation result.

Weight Function

${W_{\alpha}(r)} = {{\rho_{\alpha}( {r - R_{\alpha}} )}\lbrack {\sum\limits_{\beta}{\rho_{\beta}( {r - R_{\beta}} )}} \rbrack}^{- 1}$ρ_(α)(r − R_(α)):  spherically  average  ground-state  atomic  density$\sum\limits_{\beta}{{\rho_{\beta}( {r - R_{\beta}} )}\text{:}\mspace{14mu}{promolecule}\mspace{14mu}{density}}$

Deformation Density

${\rho_{d}(r)} = {{\rho(r)} - {\sum\limits_{\alpha}{\rho_{\alpha}( {r - R_{\alpha}} )}}}$ρ(r):  molecular  densityρ_(α)(r − R_(α)):  density  of  the  free  atom  α  located  atcoordinates  R_(α)

Atomic Chargeq(α)=−∫ρ_(d)(r)W _(α)(r)d ³ r

W_(α)(r): weight function

In an exemplary embodiment of the present specification, the organicmaterial layer including: a compound including a heteroatom; and analkali metal complex or an alkaline earth metal complex is one or two ormore layers selected from the group consisting of an electron injectionlayer, an electron transporting layer, and a hole blocking layer.

In an exemplary embodiment of the present specification, the organicmaterial layer including: a compound including a heteroatom; and analkali metal complex or an alkaline earth metal complex is an electrontransporting layer.

In another exemplary embodiment, the organic material layer including: acompound including a heteroatom; and an alkali metal complex or analkaline earth metal complex is a hole blocking layer.

The organic light emitting device having the aforementioned dipolemoment value range may provide low driving voltage and high lightemitting efficiency because the capability of injecting and transportingelectrons introduced from the cathode is improved. Further, thearrangement of the molecules in the organic light emitting device isexcellent, thereby providing a dense and compact film. Accordingly, theorganic light emitting device including an electron transportingmaterial is excellent in stability, and thus, it is possible to providean organic light emitting device having a long service life.

In an exemplary embodiment of the present specification, the differencebetween the dipole moment value of the compound after the docking andthe dipole moment value of the compound including a heteroatom beforethe docking is 3 debye or more.

In an exemplary embodiment of the present specification, the differencebetween the dipole moment value of the compound including a heteroatomafter the docking and the dipole moment value of the compound includinga heteroatom before the docking is 3 debye or more and 8 debye or less.

As in an exemplary embodiment of the present specification, it ispreferred that the organic material layer between the cathode and thelight emitting layer includes a material which smoothly transportselectrons for the low driving voltage of the organic light emittingdevice. In order to smoothly transport electrons as described above, thedipole moment value of the organic material layer is preferably 6 debyeto 13 debye, but when the dipole moment value of the compound itself isin the range of 6 debye to 13 debye, the instability of the compound maybe problematic.

As in an exemplary embodiment of the present specification, it ispossible to adjust the dipole moment value to 6 debye to 13 debye and,simultaneously, to form a highly stable organic material layer, byvarying the dipole moment values before and after the heteroatom isdocked to the alkali metal complex or the alkaline earth metal complex.Accordingly, the organic light emitting device according to an exemplaryembodiment of the present specification may provide high light emittingefficiency, and simultaneously, have a positive influence on the servicelife of the diode.

Specifically, it can be considered that the higher the differencebetween the dipole moment value of the compound including a heteroatombefore the docking and the dipole moment value of the compound includinga heteroatom after the docking is, the more stable the docking is, andthe difference is preferably 3 debye or more.

In an exemplary embodiment of the present specification, the organicmaterial layer including: a compound including a heteroatom; and analkali metal complex or an alkaline earth metal complex includes thecompound including a heteroatom and the alkali metal complex or thealkaline earth metal complex at a weight ratio of 1:9 to 9:1. The weightratio is preferably 3:7 to 7:3, and more preferably 4:6 to 6:4.

In an exemplary embodiment of the present specification, a heteroatom ofthe compound including the heteroatom includes a trivalent atom.

In an exemplary embodiment of the present specification, the compoundincluding the heteroatom is a compound including one or two or more Natoms.

The heteroatom as described above includes an unshared electron pair,and the unshared electron pair may serve as a docking site which mayfacilitate the docking of the alkali metal complex or the alkaline earthmetal complex, and electrons may be more easily transported through thedocking.

In an exemplary embodiment of the present specification, the compoundincluding the heteroatom may be an aromatic hetero ring. In the case asdescribed above, electrons may easily move because a conjugatedstructure is included in the structure of the compound.

The conjugated structure in the present specification means a structurein which two or more double bonds or triple bonds are present whileincluding each one single bond therebetween, and may mean a structure inwhich a resonance structure may be formed.

In an exemplary embodiment of the present specification, the compoundincluding the heteroatom includes any one of the following structures.

The structure is unsubstituted or substituted with one or two or moresubstituent groups selected from the group consisting of deuterium; asubstituted or unsubstituted alkyl group; a substituted or unsubstitutedaryl group; and a substituted or unsubstituted heterocyclic group, oradjacent substituent groups may combine with each other to form asubstituted or unsubstituted ring.

In an exemplary embodiment of the present specification, the alkalimetal complex or the alkaline earth metal complex is represented by thefollowing Chemical Formula 1.

In Chemical Formula 1,

Z and a dashed arc represent two or three atoms and bonds essentiallyrequired to complete a 5- or 6-membered ring together with M,

A's each represent hydrogen or a substituent,

B's each are an independently selected substituent on a Z atom, or twoor more substituents combine with each other to form a substituted orunsubstituted ring,

j is 0 to 3,

k is 1 or 2,

M is an alkali metal or an alkaline earth metal,

X is N or O, and

m and n are an integer independently selected so as to provide a neutralcharge on a complex.

Examples of the substituent groups will be described below, but thepresent specification is not limited thereto.

The term “substitution” means that a hydrogen atom bonded to a carbonatom of a compound is changed into another substituent group, and aposition to be substituted is not limited as long as the position is aposition at which the hydrogen atom is substituted, that is, a positionat which the substituent group may be substituted, and when two or moreare substituted, the two or more substituent groups may be the same asor different from each other.

In the present specification, the term “substituted or unsubstituted”means that a group is substituted with one or two or more substituentgroups selected from the group consisting of deuterium; a halogen group;a nitrile group; a nitro group; an imide group; an amide group; ahydroxy group; a substituted or unsubstituted alkyl group; a substitutedor unsubstituted cycloalkyl group; a substituted or unsubstituted alkoxygroup; a substituted or unsubstituted alkenyl group; a substituted orunsubstituted amine group; a substituted or unsubstituted aryl group;and a substituted or unsubstituted heterocyclic group or is substitutedwith a substituent group to which two or more substituent groups arelinked among the substituent groups exemplified above, or has nosubstituent group. For example, “the substituent group to which two ormore substituent groups are linked” may be a biphenyl group. That is,the biphenyl group may also be an aryl group, and may be interpreted asa substituent group to which two phenyl groups are linked.

With respect to the substituent in the present specification, one or twoor more may be selected from the group consisting of deuterium; ahalogen group; a nitrile group; a nitro group; an imide group; an amidegroup; a hydroxy group; a substituted or unsubstituted alkyl group; asubstituted or unsubstituted cycloalkyl group; a substituted orunsubstituted alkoxy group; a substituted or unsubstituted alkenylgroup; a substituted or unsubstituted amine group; a substituted orunsubstituted aryl group; and a substituted or unsubstitutedheterocyclic group.

In the present specification, the alkyl group may be straight-chained orbranched, and the number of carbon atoms thereof is not particularlylimited, but is preferably 1 to 50. Specific examples thereof include amethyl group, an ethyl group, a propyl group, an isopropyl group, abutyl group, a t-butyl group, a pentyl group, a hexyl group, a heptylgroup, and the like, but are not limited thereto.

In the present specification, the alkenyl group may be straight-chainedor branched, and the number of carbon atoms thereof is not particularlylimited, but is preferably 2 to 40. Specific examples thereof includevinyl, 1-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl,1-pentenyl, 2-pentenyl, 3-pentenyl, 3-methyl-1-butenyl, 1,3-butadienyl,allyl, 1-phenylvinyl-1-yl, 2-phenylvinyl-1-yl, 2,2-diphenylvinyl-1-yl,2-phenyl-2-(naphthyl-1-yl)vinyl-1-yl, 2,2-bis(diphenyl-1-yl)vinyl-1-yl,a stilbenyl group, a styrenyl group, and the like, but are not limitedthereto.

In the present specification, the cycloalkyl group is not limitedthereto, but has preferably 3 to 60 carbon atoms, and examples thereofinclude a cyclopentyl group, a cyclohexyl group, and the like, but arenot limited thereto.

In the present specification, the amine group may be selected from thegroup consisting of —NH₂; an alkylamine group; an aralkylamine group; anarylamine group; and a heteroarylamine group, and the number of carbonatoms thereof is not particularly limited, but is preferably 1 to 30.Specific examples of the amine group include a methylamine group, adimethylamine group, an ethylamine group, a diethylamine group, aphenylamine group, a naphthylamine group, a biphenylamine group, ananthracenylamine group, a 9-methyl-anthracenylamine group, adiphenylamine group, a phenylnaphthylamine group, a ditolylamine group,a phenyltolylamine group, a triphenylamine group, and the like, but arenot limited thereto.

When the aryl group is a monocyclic aryl group, the number of carbonatoms thereof is not particularly limited, but is preferably 6 to 25.Specific examples of the monocyclic aryl group include a phenyl group, abiphenyl group, a terphenyl group, and the like, but are not limitedthereto.

When the aryl group is a polycyclic aryl group, the number of carbonatoms thereof is not particularly limited, but is preferably 10 to 24.Specific examples of the polycyclic aryl group include a naphthyl group,a triphenylenyl group, an anthracenyl group, a phenanthryl group, apyrenyl group, a perylenyl group, a chrysenyl group, a fluorenyl group,and the like, but are not limited thereto.

In the present specification, the fluorenyl group may be substituted,and adjacent substituent groups may combine with each other to form aring.

When the fluorenyl group is substituted, the substituent may be

However, the fluorenyl group is not limited thereto.

In the present specification, the heterocyclic group includes one ormore of an atom other than carbon, that is, a heteroatom, andspecifically, the heteroatom may include one or more atoms selected fromthe group consisting of O, N, Se, and S, and the like. The number ofcarbon atoms thereof is not particularly limited, but is preferably 2 to60. Examples of the heterocyclic group include a thiophene group, afuran group, a pyrrole group, an imidazole group, a triazole group, anoxazole group, an oxadiazole group, a triazole group, a pyridyl group, abipyridyl group, a pyrimidyl group, a triazine group, an acridyl group,a pyridazine group, a pyrazinyl group, a qinolinyl group, a quinazolinegroup, a quinoxalinyl group, a phthalazinyl group, a pyridopyrimidinylgroup, a pyridopyrazinyl group, a pyrazinopyrazinyl group, anisoquinoline group, an indole group, a carbazole group, a benzoxazolegroup, a benzimidazole group, a benzothiazole group, a benzocarbazolegroup, a benzothiophene group, a dibenzothiophene group, a benzofuranylgroup, a phenanthroline group, a thiazolyl group, an isoxazolyl group,an oxadiazolyl group, a thiadiazolyl group, a benzothiazolyl group, aphenothiazinyl group, a dibenzofuranyl group, and the like, but are notlimited thereto.

The heterocyclic group may be monocyclic or polycyclic, and may be anaromatic ring, an aliphatic ring, or a condensed ring of the aromaticring and the aliphatic ring.

When two or more substituents combine with each other to form asubstituted or unsubstituted ring, the two or more substituents areprovided while being adjacent to each other.

In the present specification, the term “adjacent” may mean a substituentsubstituted with an atom directly linked to an atom in which thecorresponding substituent is substituted, a substituent disposedsterically closest to the corresponding substituent group, or anothersubstituent substituted with an atom in which the correspondingsubstituent is substituted. For example, two substituent groupssubstituted at the ortho position in a benzene ring and two substituentssubstituted with the same carbon in an aliphatic ring may be interpretedas groups which are “adjacent” to each other.

In the present specification, examples of the ring structure, which isformed by combining the two or more substituents with each other,include an aromatic ring, an aliphatic ring, and the like, and may bemonocyclic or polycyclic.

In an exemplary embodiment of the present specification, the alkalimetal complex or the alkaline earth metal complex represented byChemical Formula 1 is represented by the following Chemical Formula 1-aor 1-b.

In Chemical Formulae 1-a and 1-b,

the definitions of M, m, and n are the same as those described above,

a and b are each an integer of 1 to 3,

when a and b are 2 or more, two or more structures in the parenthesisare the same as or different from each other, and

Ra, Rb, and Y1 to Y3 are the same as or different from each other, andare each independently hydrogen or a substituent, or two or moresubstituents combine with each other to form a substituted orunsubstituted ring.

In an exemplary embodiment of the present specification, the alkalimetal complex or the alkaline earth metal complex represented byChemical Formula 1 is represented by any one of the following ChemicalFormulae 1-1 to 1-26.

Ph means a phenyl group, Me means a methyl group, and t-Bu means at-butyl group.

In an exemplary embodiment of the present specification, the differencebetween the LUMO energy level of the organic material layer adjacent tothe light emitting layer among the one or more organic material layersprovided between the cathode and the light emitting layer and the LUMOenergy level of the light emitting layer is 1 eV or less.

Specifically, in an exemplary embodiment of the present specification,the difference between the LUMO energy level of the organic materiallayer adjacent to the light emitting layer among the one or more organicmaterial layers provided between the cathode and the light emittinglayer and the LUMO energy level of the light emitting layer is 0 eV ormore and 1 eV or less.

When the difference between the LUMO energy level of the organicmaterial layer adjacent to the light emitting layer among the one ormore organic material layers provided between the cathode and the lightemitting layer and the LUMO energy level of the light emitting layer ismore than 1 eV, the movement of electrons from the cathode to the lightemitting layer is stagnated to apply an excessive load on the diode, sothat the diode is disadvantageous in terms of the service life.Accordingly, as in an exemplary embodiment of the present specification,when the difference between the LUMO energy level of the organicmaterial layer adjacent to the light emitting layer among the one ormore organic material layers provided between the cathode and the LUMOenergy level of the light emitting layer and the light emitting layer is1 eV or less, the movement of electrons is facilitated, so that thediode may be advantageous in terms of the efficiency of the diode.

In the present specification, the energy level means the size of energy.Accordingly, even when the energy level is expressed in the negative (−)direction from the vacuum level, it is interpreted that the energy levelmeans an absolute value of the corresponding energy value. For example,the HOMO energy level means the distance from the vacuum level to thehighest occupied molecular orbital. Further, the LUMO energy level meansthe distance from the vacuum level to the lowest unoccupied molecularorbital.

For the measurement of the HOMO energy level in the presentspecification, it is possible to use a UV photoelectron spectroscopy(UPS) for measuring the ionization potential of the material byirradiating UV on the surface of the thin film and detecting electronsjumping out in this case. Otherwise, for the measurement of the HOMOenergy level, it is possible to use a cyclic voltammetry (CV) fordissolving a material to be measured along with an electrolytic solutionin a solvent, and then measuring the oxidation potential through thevoltage sweep. Furthermore, it is possible to use a method ofphotoemission yield spectrometer in air (PYSA), which measures theionization potential in the atmosphere by using a machine of AC-3(manufactured by RKI Instruments, Inc.).

Specifically, the HOMO energy level of the present specification wasmeasured by vacuum depositing a target material to have a thickness of50 nm or more on an ITO substrate, and then using an AC-3 measuringinstrument (manufactured by RKI Instruments, Inc.). Further, for theLUMO energy level, the absorption spectrum (abs.) and photoluminescencespectrum (PL) of the sample prepared above were measured, and then eachspectrum edge energy was calculated, the difference was taken as abandgap (Eg), and the LUMO energy level was calculated as a valueobtained by subtracting the bandgap difference from the HOMO energylevel measured from the AC-3.

In the present specification, the LUMO energy level may be obtainedthrough the measurement of inverse photoelectron spectroscopy (IPES) orelectrochemical reduction potential. The IPES is a method fordetermining the LUMO energy level by irradiating electron beam on a thinfilm, and measuring light emitting in this case. In addition, for themeasurement of electrochemical reduction potential, a measurement targetmaterial is dissolved along with the electrolytic solution in a solvent,and then the reduction potential may be measured through the voltagesweep. Otherwise, the LUMO energy level may be calculated by using theHOMO energy level and a singlet energy level obtained by measuring theUV absorption degree of the target material.

In an exemplary embodiment of the present specification, the lightemitting layer includes a phosphorescent dopant. As described above,when a phosphorescent dopant is used, the light emitting efficiency isbetter than the light emitting efficiency when only a fluorescent dopantis included, but there may occur a problem in that the durabilitydeteriorates. However, when the diode includes an organic material layerin which the dipole moment value of the compound including theheteroatom after the docking according to an exemplary embodiment of thepresent specification is 6 debye to 13 debye, the durability may beincreased because electrons are smoothly transported. Accordingly, theorganic light emitting device according to an exemplary embodiment ofthe present specification may provide a diode having high efficiency anda long service life.

In an exemplary embodiment of the present specification, the organiclight emitting device may include two or more light emitting layers. Thetwo or more light emitting layers may also be provided while being incontact with each other, and may also be provided while including anadditional organic material layer between the two or more light emittinglayers.

In an exemplary embodiment of the present specification, the organiclight emitting device includes two or more light emitting layers andincludes a charge generation layer between two adjacent light emittinglayers in the two or more light emitting layers, and the chargegeneration layer may include an n-type organic material layer and ap-type organic material layer.

In another exemplary embodiment, the n-type organic material layer andthe p-type organic material layer, which are included in the chargegeneration layer, form an NP junction.

In an exemplary embodiment of the present specification, the p-typeorganic material layer is selected from the group consisting of a holeinjection layer, a hole transporting layer, an electron blocking layer,and a light emitting layer, and the n-type organic material layer isselected from the group consisting of an electron transporting layer, anelectron injection layer, a hole blocking layer, and a light emittinglayer.

In the present specification, the n-type means n-type semiconductorcharacteristics. In other words, the n-type is a characteristic in thatelectrons are injected or transported through the lowest unoccupiedmolecular orbital (LUMO) energy level, and this may be defined as acharacteristic of a material having a mobility of electrons larger thanthat of holes. In contrast, the p-type means p-type semiconductorcharacteristics. In other words, the p-type is a characteristic in thatholes are injected or transported through the highest occupied molecularorbital (HOMO) energy level, and this may be defined as a characteristicof a material having a mobility of holes larger than that of electrons.In the present specification, a compound or an organic material layerhaving n-type characteristics may be mentioned as an n-type compound oran n-type organic material layer. Further, a compound or organicmaterial layer having p-type characteristics may be mentioned as ap-type compound or a p-type organic material layer. In addition, then-type doping may mean that a doping is conducted so as to have n-typecharacteristics.

In the present specification, a charge generation layer is a layer ofgenerating charges without the application of an external voltage, andgenerates charges between adjacent light emitting layers in two or morelight emitting layers to allow the two or more light emitting layersincluded in the organic light emitting device to be capable of emittinglight.

The NP junction in the present specification may mean not only physicalcontact of a second electron transporting layer, which is an n-typeorganic material layer, with the p-type organic material layer, but alsointeraction which may easily generate and transport holes and electrons.

According to an exemplary embodiment of the present specification, whenan NP junction is formed, holes or electrons may be easily formed by anexternal voltage or light source. Accordingly, it is possible to preventa driving voltage for injecting holes from being increased.

In another exemplary embodiment, the peak wavelengths of thephotoluminescence spectra of at least two layers in the two or morelight emitting layers are the same as or different from each other.

The peak wavelength in the present specification means a wavelength atthe maximum value in the spectral distribution.

In an exemplary embodiment of the present specification, the peakwavelengths of the photoluminescence spectra of at least two layers inthe two or more light emitting layers are different from each other.

In an exemplary embodiment of the present specification, at least one ofthe two or more light emitting layers includes a phosphorescent dopant,and at least one thereof includes a fluorescent dopant.

As in an exemplary embodiment of the present specification, a whitelight emitting diode may be manufactured by stacking blue fluorescence,green phosphorescence, and red phosphorescence; and stacking bluefluorescence and green and yellow phosphorescence, by including the twoor more light emitting layers which are different from each other.Specifically, the organic light emitting device according to anexemplary embodiment of the present specification may include afluorescent light emitting layer and/or a phosphorescent light emittinglayer.

For example, in the case of blue, the peak wavelength of thephotoluminescence spectrum is 400 nm to 500 nm, in the case of green,the peak wavelength of the photoluminescence spectrum is 510 nm to 580nm, and in the case of red, the peak wavelength of the photoluminescencespectrum is 610 nm to 680 nm, and the person skilled in the art may uselight emitting layers having different peak wavelengths in combinationof one layer or two layers or more, if necessary.

As the phosphorescent dopant and the fluorescent dopant in the presentspecification, dopants commonly used in the art may be used.

In an exemplary embodiment of the present specification, the organiclight emitting device includes: a first light emitting layer provided onan organic material layer including: a compound including a heteroatom;and an alkali metal complex or an alkaline earth metal complex; and asecond light emitting layer provided on the first light emitting layer.

In this case, the first light emitting layer and the second lightemitting layer may be provided while being brought into contact witheach other, and an additional organic material layer may be providedbetween the first light emitting layer and the second light emittinglayer.

In another exemplary embodiment of the present specification, theorganic light emitting device includes: a first light emitting layerprovided at a portion on an organic material layer including: a compoundincluding a heteroatom; and an alkali metal complex or an alkaline earthmetal complex; and a second light emitting layer provided at the otherportion on the organic material layer including: a compound including aheteroatom; and an alkali metal complex or an alkaline earth metalcomplex.

In this case, the first light emitting layer and the second lightemitting layer may be provided side by side on the same surface of theorganic material layer including: a compound including a heteroatom; andan alkali metal complex or an alkaline earth metal complex. In oneexemplary embodiment, one side surface of the first light emitting layerand one side surface of the second light emitting layer may be providedwhile being brought into contact with each other.

In an exemplary embodiment of the present specification, the first lightemitting layer and the second light emitting layer, which are providedside by side, may be provided while being brought into contact with thesame surface of the organic material layer including: a compoundincluding a heteroatom; and an alkali metal complex or an alkaline earthmetal complex.

In another exemplary embodiment, an additional layer may be providedbetween the first light emitting layer and the second light emittinglayer, which are provided side by side, and the organic material layerincluding: a compound including a heteroatom; and an alkali metalcomplex or an alkaline earth metal complex. In an exemplary embodimentof the present specification, the additional layer may be a holeblocking layer and/or an electron transporting layer.

For example, the structure of the organic light emitting device of thepresent specification may have a structure as illustrated in FIGS. 1 to3, but is not limited thereto.

FIG. 1 illustrates the structure of an organic light emitting device inwhich an anode (201), a hole transporting layer (301), a light emittinglayer (401), an electron transporting layer (501), and a cathode (601)are sequentially stacked on a substrate (101). In FIG. 1, the electrontransporting layer (501) may be the organic material layer including: acompound including a heteroatom; and an alkali metal complex or analkaline earth metal complex.

FIG. 2 illustrates the structure of an organic light emitting device inwhich an anode (201), a hole transporting layer (301), a second lightemitting layer (402), a first light emitting layer (403), an electrontransporting layer (501), and a cathode (601) are sequentially stackedon a substrate (101). In FIG. 2, the electron transporting layer (501)may be the organic material layer including: a compound including aheteroatom; and an alkali metal complex or an alkaline earth metalcomplex, and the second light emitting layer (402) and the first lightemitting layer (403) may be provided while being brought into contactwith each other, include an additional organic material layer, andfurther include a third light emitting layer.

FIG. 3 illustrates the structure of an organic light emitting device inwhich an anode (201) and a hole transporting layer (301) are provided ona substrate (101), a second light emitting layer (402) and a first lightemitting layer (403) are provided on the hole transporting layer (301),and an electron transporting layer (501) and a cathode (601) aresequentially stacked on the first light emitting layer (403) and thesecond light emitting layer (402). In FIG. 3, the electron transportinglayer (501) may be the organic material layer including: a compoundincluding a heteroatom; and an alkali metal complex or an alkaline earthmetal complex.

FIGS. 1 to 3 illustrate an exemplified structure according to exemplaryembodiments of the present specification, and may further include otherorganic material layers. Further, the organic material layer including:a compound including a heteroatom; and an alkali metal complex or analkaline earth metal complex may also be a hole blocking layer insteadof the electron transporting layer (501).

In an exemplary embodiment of the present specification, the organiclight emitting device may further include one or more layers selectedfrom the group consisting of a hole injection layer, a hole transportinglayer, an electron transporting layer, an electron injection layer, anelectron blocking layer, and a hole blocking layer.

The organic light emitting device of the present specification may bemanufactured by materials and methods known in the art, except forincluding one or more organic material layers, which include: a compoundincluding a heteroatom; and an alkali metal complex or an alkaline earthmetal complex and are provided between the cathode and the lightemitting layer.

For example, the organic light emitting device of the presentspecification may be manufactured by sequentially stacking an anode, anorganic material layer, and a cathode on a substrate. In this case, theorganic light emitting device may be manufactured by depositing a metalor a metal oxide having conductivity, or an alloy thereof on a substrateto form an anode by using a physical vapor deposition (PVD) method suchas sputtering or e-beam evaporation, forming an organic material layerincluding a hole injection layer, a hole transporting layer, an electronblocking layer, a light emitting layer, an electron transporting layer,and an electron injection layer thereon, and then depositing a materialwhich may be used as a cathode thereon. In addition to the methoddescribed above, an organic light emitting device may be made bysubsequently depositing a cathode material, an organic material layer,and an anode material on a substrate. In addition to the methoddescribed above, an organic light emitting device may be made bysubsequently depositing an anode material, an organic material layer,and a cathode material on a substrate.

The organic material layer of the organic light emitting device of thepresent specification may be composed of a multi-layered structure inwhich one or more organic material layers are stacked.

When the organic light emitting device includes a plurality of organicmaterial layers, the organic material layer may be formed of the samematerial or different materials.

As the anode material, a material having a large work function isusually preferred so as to smoothly inject holes into an organicmaterial layer. Specific examples of the anode material which may beused in the present specification include: a metal, such as vanadium,chromium, copper, zinc, and gold, or alloys thereof; a metal oxide, suchas zinc oxide, indium oxide, indium tin oxide (ITO), and indium zincoxide (IZO); a combination of metal and oxide, such as ZnO:Al orSnO₂:Sb; an electrically conductive polymer, such aspoly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene](PEDOT), polypyrrole, and polyaniline, and the like, but are not limitedthereto.

As the cathode material, a material having a small work function isusually preferred so as to smoothly inject electrons into an organicmaterial layer. Specific examples of the cathode material include: ametal, such as magnesium, calcium, sodium, potassium, titanium, indium,yttrium, lithium, gadolinium, aluminum, silver, tin, and lead, or alloysthereof; a multi-layered structural material, such as LiF/Al or LiO₂/Al,and the like, but are not limited thereto.

The hole injection material is a layer which injects holes from anelectrode, and is preferably a compound which has a capability oftransporting holes, and thus has an effect of injecting holes at ananode and an excellent effect of injecting holes for a light emittinglayer or a light emitting material, prevents excitons produced from alight emitting layer from moving to an electron injection layer or anelectron injection material, and is excellent in the ability to form athin film. It is preferred that the highest occupied molecular orbital(HOMO) of the hole injection material is between the work function ofthe anode material and the HOMO of a peripheral organic material layer.Specific examples of the hole injection material include metalporphyrin, oligothiophene, an arylamine-based organic material, ahexanitrile hexaazatriphenylene-based organic material, aquinacridone-based organic material, a perylene-based organic material,anthraquinone, a polyaniline and polythiophene-based electricallyconductive polymer, and the like, but are not limited thereto.

The hole transporting layer is a layer which receives holes from a holeinjection layer and transports the holes to a light emitting layer, anda hole transporting material is a material which may receive holes froman anode or a hole injection layer to transfer the holes to a lightemitting layer, and is suitably a material having large mobility for theholes. Specific examples thereof include an arylamine-based organicmaterial, an electrically conductive polymer, a block copolymer in whicha conjugate portion and a non-conjugate portion are present together,and the like, but are not limited thereto.

The light emitting material is a material which may receive holes andelectrons from a hole transporting layer and an electron transportinglayer, respectively, and combine the holes and the electrons to emitlight in a visible ray region, and is preferably a material having goodquantum efficiency to fluorescence or phosphorescence. Specific examplesthereof include: a 8-hydroxy-quinoline aluminum complex (Alq₃); acarbazole-based compound; a dimerized styryl compound; BAlq; a10-hydroxybenzoquinoline-metal compound; a benzoxazole, benzthiazole andbenzimidazole-based compound; a poly(p-phenylenevinylene (PPV)-basedpolymer; a spiro compound; polyfluorene, lubrene, and the like, but arenot limited thereto.

The light emitting layer may include a host material and a dopantmaterial. Examples of the host material include a condensed aromaticring derivative, or a hetero ring-containing compound, and the like.Specifically, examples of the condensed aromatic ring derivative includean anthracene derivative, a pyrene derivative, a naphthalene derivative,a pentacene derivative, a phenanthrene compound, a fluoranthenecompound, and the like, and examples of the hetero ring-containingcompound include a carbazole derivative, a dibenzofuran derivative, aladder-type furan compound, a pyrimidine derivative, and the like, butthe examples thereof are not limited thereto.

In the fluorescence light emitting layer, as the host material, one ortwo or more are selected from the group consisting of distyrylarylene(DSA), a distyrylarylene derivative, distyrylbenzene (DSB), adistyrylbenzene derivative, 4,4′-bis(2,2′-diphenyl vinyl)-1,1′-biphenyl(DPVBi), a DPVBi derivative, spiro-DPVBi, and spiro-6P.

In the fluorescence light emitting layer, as the dopant material, one ortwo or more are selected from the group consisting of styrylamine-based,pherylene-based, and distyrylbiphenyl (DSBP)-based dopant materials.

The electron injection layer is a layer which injects electrons from anelectrode, and is preferably a compound which has a capability oftransporting electrons, has an effect of injecting electrons from acathode and an excellent effect of injecting electrons into a lightemitting layer or a light emitting material, prevents excitons producedfrom the light emitting layer from moving to the hole injection layer,and is also excellent in the ability to form a thin film. Specificexamples thereof include fluorenone, anthraquinodimethane,diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole,imidazole, perylenetetracarboxylic acid, fluorenylidene methane,anthrone and derivatives thereof, a metal complex compound, anitrogen-containing 5-membered ring derivative, and the like, but arenot limited thereto.

Examples of the metal complex compound include 8-hydroxyquinolinatolithium, bis(8-hydroxyquinolinato) zinc, bis(8-hydroxyquinolinato)copper, bis(8-hydroxyquinolinato) manganese, tris(8-hydroxyquinolinato)aluminum, tris(2-methyl-8-hydroxyquinolinato) aluminum,tris(8-hydroxyquinolinato) gallium, bis(10-hydroxybenzo[h]quinolinato)beryllium, bis(10-hydroxybenzo[h]quinolinato) zinc,bis(2-methyl-8-quinolinato) chlorogallium, bis(2-methyl-8-quinolinato)(o-cresolato) gallium, bis(2-methyl-8-quinolinato) (1-naphtholato)aluminum, bis(2-methyl-8-quinolinato) (2-naphtholato) gallium, and thelike, but are not limited thereto.

The hole blocking layer is a layer which blocks holes from reaching acathode, and may be generally formed under the same conditions as thoseof the hole injection layer. Specific examples thereof include anoxadiazole derivative or a triazole derivative, a phenanthrolinederivative, BCP, an aluminum complex, and the like, but are not limitedthereto.

The organic light emitting device according to the present specificationmay be a top emission type, a bottom emission type, or a dual emissiontype according to the material to be used.

In addition, the organic light emitting device according to the presentspecification may be a normal type in which a lower electrode is ananode and an upper electrode is a cathode, and may also be an invertedtype in which a lower electrode is a cathode and an upper electrode isan anode.

The structure according to an exemplary embodiment of the presentspecification may be operated by a principle which is similar to theprinciple applied to an organic light emitting device, even in anorganic electronic diode including an organic solar cell, an organicphotoconductor, an organic transistor, and the like.

MODE FOR INVENTION

Hereinafter, the present specification will be described in detail withreference to the Examples for specifically describing the presentspecification. However, the Examples according to the presentspecification may be modified in various forms, and it is notinterpreted that the scope of the present specification is limited tothe Examples described below in detail. The Examples of the presentspecification are provided for more completely explaining the presentspecification to the person with ordinary skill in the art.

Experimental Examples 1-1 to 1-10

The results of calculating the dipole moments of the compounds includinga heteroatom, which are represented by the following Chemical FormulaeST1 to ST9, before and after being docked to lithium quinolate (LiQ),and the result of calculating the dipole moments of the compoundincluding a heteroatom, which is represented by the following ChemicalFormula ST10, before and after being docked to lithium hydride (LiH) areshown in Table 1.

Comparative Examples 1-1 to 1-7

The results of calculating the dipole moments of the compounds includinga heteroatom, which are represented by the following Chemical FormulaeET1, ET2, and ET5 to ET7, before and after being docked to lithiumquinolate (LiQ), and the result of calculating the dipole moments of thecompounds including a heteroatom, which are represented by the followingChemical Formulae ET3 and ET4, before and after being docked to lithiumhydride (LiH) are shown in Table 1.

TABLE 1 Absolute value of dipole moment before Chemical Dipole momentDipole moment docking − dipole Formula before docking after dockingmoment after docking ST1 1.62 9.09 7.47 ST2 4.97 12.07 7.1 ST3 1.34 7.195.85 ST4 4.1 11.3 7.2 ST5 0.22 6.51 6.29 ST6 3.28 10.35 7.07 ST7 5.49.85 4.45 ST8 3.7 7.13 3.43 ST9 1.76 6.5 4.74 ST10 3.58 8.81 5.23 ET10.41 5.93 5.52 ET2 0.16 4.93 4.77 ET3 4.95 3.48 1.47 ET4 4.84 3.6 1.24ET5 6.41 13.71 7.3 ET6 6.66 8.28 1.62 ET7 7.01 9.34 2.33

Experimental Example 2-1

A glass substrate thinly coated with indium tin oxide (ITO) to have athickness of 500 Å was put into distilled water in which a detergent wasdissolved, and ultrasonically washed. In this case, a productmanufactured by the Fischer Co., was used as the detergent, anddistilled water twice filtered using a filter manufactured by MilliporeCo., was used as the distilled water. After the ITO was washed for 30minutes, ultrasonic washing was conducted repeatedly twice usingdistilled water for 10 minutes. After the washing using distilled waterwas completed, ultrasonic washing was conducted using isopropyl alcohol,acetone, and methanol solvents, and drying was conducted, and then theproduct was transferred to a plasma cleaner. In addition, the substratewas cleaned using oxygen plasma for 5 minutes, and then transferred to avacuum evaporator.

The following Chemical Formula [HAT] was thermally vacuum deposited tohave a thickness of 50 Å on a transparent ITO electrode, which wasprepared as described above, thereby forming a hole injection layer. Thefollowing Chemical Formula [NPB] was vacuum deposited to have athickness of 1,100 Å on the hole injection layer, thereby forming a holetransporting layer. The following Chemical Formula [HT-A] was vacuumdeposited to have a thickness of 200 Å on the hole transporting layer,thereby forming an electron blocking layer.

Subsequently, the following Chemical Formulae [BH] and [BD] were vacuumdeposited at a weight ratio of 25:1 to have a film thickness of 350 Å onthe electron blocking layer, thereby forming a light emitting layer.

The following Chemical Formula ST1 and the following Chemical Formula[LiQ] were vacuum deposited at a weight ratio of 1:1 on the lightemitting layer, thereby forming an electron transporting layer having athickness of 200 Å. Aluminum was deposited to have a thickness of 1,000Å on the electron transporting layer, thereby forming a cathode.

In the aforementioned procedure, the deposition rate of the organicmaterial was maintained at 0.4 to 0.9 Å/sec, the deposition rates oflithium fluoride and aluminum of the cathode were maintained at 0.3Å/sec and at 2 Å/sec, respectively, and the degree of vacuum during thedeposition was maintained at 1×10⁻⁷ to 5×10⁻⁸ torr, therebymanufacturing an organic light emitting device.

Experimental Example 2-2

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ST2] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Experimental Example 2-3

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ST3] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Experimental Example 2-4

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ST4] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Experimental Example 2-5

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ST5] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Experimental Example 2-6

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ST6] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Experimental Example 2-7

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ST7] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Experimental Example 2-8

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ST8] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Experimental Example 2-9

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ST9] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Experimental Example 2-10

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ST10] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Comparative Example 2-1

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ET1] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Comparative Example 2-2

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ET2] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Comparative Example 2-3

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ET3] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Comparative Example 2-4

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ET4] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Comparative Example 2-5

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ET5] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Comparative Example 2-6

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ET6] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

Comparative Example 2-7

An organic light emitting device was manufactured in the same manner asin [Experimental Example 2-1], except that [ET7] was used instead of[Chemical Formula ST1] of [Experimental Example 2-1].

For the organic light emitting devices manufactured by theabove-described method, the driving voltage and the light emittingefficiency were measured at a current density of 10 mA/cm², and a timeT90 for reaching a 90% value compared to the initial luminance wasmeasured at a current density of 20 mA/cm². The results are shown in thefollowing Table 2.

TABLE 2 Service life (h) Voltage Efficiency Color coordinate T₉₀ at (V)(Cd/A) (x, y) 20 mA/cm² Experimental 4.32 6.42 (0.138, 0.112) 157Example 2-1 Experimental 3.92 6.95 (0.138, 0.111) 170 Example 2-2Experimental 4.06 6.71 (0.138, 0.112) 152 Example 2-3 Experimental 4.056.75 (0.138, 0.110) 152 Example 2-4 Experimental 4.22 6.53 (0.138,0.110) 192 Example 2-5 Experimental 4.38 6.53 (0.138, 0.112) 157 Example2-6 Experimental 4.05 6.75 (0.138, 0.110) 187 Example 2-7 Experimental4.51 6.22 (0.138, 0.112) 171 Example 2-8 Experimental 4.38 6.53 (0.138,0.113) 181 Example 2-9 Experimental 4.32 6.42 (0.138, 0.112) 157 Example2-10 Comparative 5.1 4.42 (0.138, 0.114) 92 Example 2-1 Comparative 5.124.32 (0.138, 0.115) 53 Example 2-2 Comparative 4.75 5.32 (0.138, 0.115)112 Example 2-3 Comparative 4.88 5.29 (0.138, 0.114) 132 Example 2-4Comparative 5.22 5.3 (0.137, 0.113) 93 Example 2-5 Comparative 4.68 5.91(0.136, 0.111) 149 Example 2-6 Comparative 4.66 5.89 (0.137, 0.114) 144Example 2-7

From the observation of the results in Table 2, it can be confirmed thatthe organic light emitting device, which includes an organic materiallayer in which a compound including a heteroatom after the docking has adipole moment of 6 debye to 13 debye, has a lower driving voltage andhigher efficiency than the organic light emitting device, which includesan organic material layer in which the compound including a heteroatomafter the docking has a dipole moment of less than 6 debye or more than13 debye.

Experimental Example 3-1

A glass substrate thinly coated with indium tin oxide (ITO) to have athickness of 1,500 Å was put into distilled water in which a detergentwas dissolved, and ultrasonically washed. In this case, a productmanufactured by the Fischer Co., was used as the detergent, anddistilled water twice filtered using a filter manufactured by MilliporeCo., was used as the distilled water. After the ITO was washed for 30minutes, ultrasonic washing was conducted repeatedly twice usingdistilled water for 10 minutes. After the washing using distilled waterwas completed, ultrasonic washing was conducted using isopropyl alcohol,acetone, and methanol solvents, and drying was conducted, and then theproduct was transferred to a plasma cleaner. In addition, the substratewas cleaned using oxygen plasma for 5 minutes, and then transferred to avacuum evaporator.

Chemical Formula [HAT] was thermally vacuum deposited to have athickness of 500 Å on a transparent ITO electrode, which was prepared asdescribed above, thereby forming a hole injection layer.

The [NPB] compound having the structure was thermally vacuum depositedto a thickness of 400 Å on the hole injection layer, thereby forming ahole transporting layer. Subsequently, a compound of the followingChemical Formula [H1] was vacuum deposited to have a film thickness of300 Å at a concentration of 10% with respect to an Ir(ppy)₃ dopant onthe hole transporting layer, thereby forming a light emitting layer.

An electron transporting material as described below was vacuumdeposited to have a thickness of 200 Å on the light emitting layer,thereby forming a layer which injects and transports electrons.

Chemical Formula ST1 and Chemical Formula [LiQ] were vacuum deposited ata weight ratio of 1:1 on the light emitting layer, thereby forming anelectron transporting layer having a thickness of 200 Å. Aluminum wasdeposited to have a thickness of 1,000 Å on the electron transportinglayer, thereby forming a cathode.

In the aforementioned procedure, the deposition rate of the organicmaterial was maintained at 0.4 to 0.7 Å/sec, the deposition rates oflithium fluoride and aluminum of the cathode were maintained at 0.3Å/sec and at 2 Å/sec, respectively, and the degree of vacuum during thedeposition was maintained at 2×10⁻⁷ to 5×10⁻⁸ torr, therebymanufacturing an organic light emitting device.

Experimental Example 3-2

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ST2] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Experimental Example 3-3

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ST3] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Experimental Example 3-4

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ST4] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Experimental Example 3-5

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ST5] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Experimental Example 3-6

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ST6] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Experimental Example 3-7

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ST7] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Experimental Example 3-8

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ST8] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Experimental Example 3-9

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ST9] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Experimental Example 3-10

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ST10] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Comparative Example 3-1

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ET1] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Comparative Example 3-2

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ET2] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Comparative Example 3-3

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ET3] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Comparative Example 3-4

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ET4] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Comparative Example 3-5

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ET5] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Comparative Example 3-6

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ET6] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

Comparative Example 3-7

An organic light emitting device was manufactured in the same manner asin [Experimental Example 3-1], except that [ET7] was used instead of[Chemical Formula ST1] of [Experimental Example 3-1].

For the organic light emitting devices manufactured by theabove-described method, the driving voltage and the light emittingefficiency were measured at a current density of 10 mA/cm². The resultsare shown in the following Table 3.

TABLE 3 Voltage Efficiency Color coordinate (V) (Cd/A) (x, y)Experimental 3.43 43.72 (0.368, 0.632) Example 3-1 Experimental 3.3242.95 (0.368, 0.610) Example 3-2 Experimental 3.53 41.15 (0.365, 0.619)Example 3-3 Experimental 3.41 45.15 (0.365, 0.621) Example 3-4Experimental 3.82 46.8 (0.368, 0.612) Example 3-5 Experimental 3.54 44.5(0.378, 0.617) Example 3-6 Experimental 3.77 41.2 (0.372, 0.623) Example3-7 Experimental 3.72 45.9 (0.378, 0.613) Example 3-8 Experimental 3.8643.3 (0.368, 0.622) Example 3-9 Experimental 3.68 46.5 (0.378, 0.611)Example 3-10 Comparative 4.64 38.9 (0.369, 0.611) Example 3-1Comparative 4.59 35.15 (0.366, 0.601) Example 3-2 Comparative 4.76 36.27(0.368, 0.626) Example 3-3 Comparative 4.81 36.25 (0.366, 0.613) Example3-4 Comparative 4.86 36.27 (0.365, 0.618) Example 3-5 Comparative 4.0740.22 (0.364, 0.611) Example 3-6 Comparative 4.1 41.35 (0.365, 0.618)Example 3-7

From the observation of the results in Table 3, it can be confirmed thatthe organic light emitting device, which includes an organic materiallayer in which a compound including a heteroatom after the docking has adipole moment of 6 debye to 13 debye, has a lower driving voltage andhigher efficiency than the organic light emitting device, which includesan organic material layer in which the compound including a heteroatomafter the docking has a dipole moment of less than 6 debye or more than13 debye.

The invention claimed is:
 1. An organic light emitting devicecomprising: a cathode; an anode; a light emitting layer provided betweenthe cathode and the anode; and at least one organic material layerprovided between the cathode and the light emitting layer, wherein theat least one organic material layer provided between the cathode and thelight emitting layer comprises: a compound including a heteroatom; andan alkali metal complex or an alkaline earth metal complex, and at leastone of the heteroatoms of the compound including a heteroatom is dockedwith the alkali metal complex or the alkaline earth metal complex, thecompound comprising the heteroatom before the docking has a dipolemoment of less than 6 debye, the compound comprising the heteroatomafter the docking has a dipole moment of 6 debye to 13 debye, whereinthe compound comprising a heteroatom comprises any one of the followingstructures:

each of which are unsubstituted or substituted with one or moresubstituent groups selected from the group consisting of deuterium, analkyl group, an aryl group, and a heterocyclic group, wherein thesubstituent group may be further substituted with one or more selectedfrom the group consisting of an alkyl group, a cycloalkyl group, an arylgroup, and a heterocyclic group, and wherein the substituent group mayhave two or more groups linked to each other, and wherein the alkalimetal complex or the alkaline earth metal complex is represented by thefollowing Chemical Formula 1:

wherein in Chemical Formula 1, Z and a dashed arc represent two or threeatoms and bonds essentially required to complete a 5- or 6-membered ringtogether with M; each A independently represents hydrogen or asubstituent, each B is an independently selected substituent on a Zatom, or two or more B's combine with each other to form a substitutedor unsubstituted ring, j is 0 to 3, k is 1 or 2, M is an alkali metal oran alkaline earth metal, X is N or O, and m and n are an integerindependently selected so as to provide a neutral charge on the alkalimetal complex or the alkaline metal complex, with the proviso that thecompound comprising a heteroatom does not include a P═O group.
 2. Theorganic light emitting device of claim 1, wherein the light emittinglayer comprises a phosphorescent dopant.
 3. The organic light emittingdevice of claim 1, wherein the at least one organic material layer isselected from the group consisting of an electron injection layer, anelectron transporting layer, and a hole blocking layer.
 4. The organiclight emitting device of claim 1, wherein a difference between a dipolemoment value of the compound comprising the heteroatom after the dockingand a dipole moment value of the compound comprising the heteroatombefore the docking is 3 debye to 8 debye.
 5. The organic light emittingdevice of claim 1, wherein the at least one organic material layercomprises the compound including a heteroatom and the alkali metalcomplex or the alkaline earth metal complex at a weight ratio of 1:9 to9:1.
 6. The organic light emitting device of claim 1, wherein theorganic light emitting device comprises two or more light emittinglayers.
 7. The organic light emitting device of claim 6, wherein peakwavelengths of the photoluminescence spectra of at least two layers inthe two or more light emitting layers are different from each other. 8.The organic light emitting device of claim 6, wherein at least one ofthe two or more light emitting layers comprises a phosphorescent dopant,and at least one thereof comprises a fluorescent dopant.
 9. The organiclight emitting device of claim 1, wherein the organic light emittingdevice comprises: a first light emitting layer provided on the at leastone organic material layer and a second light emitting layer provided onthe first light emitting layer.
 10. The organic light emitting device ofclaim 1, wherein the organic light emitting device comprises: a firstlight emitting layer provided at on a portion of Off the at least oneorganic material layer, and a second light emitting layer provided onanother portion of the at least one organic material layer.
 11. Theorganic light emitting device of claim 1, further comprising: at leastone layer selected from the group consisting of a hole injection layer,a hole transporting layer, an electron transporting layer, an electroninjection layer, an electron blocking layer, and a hole blocking layer.